The present invention relates to a clamping apparatus for works, and more particularly to a clamping apparatus which can be used for different kinds of works.
To improve productivity, dedicated processing machines have been conventionally used in accordance with works to be machined. For example, there has been proposed a dedicated processing machine of a rotary table type, in which each of the pallets arranged on the rotary table clamps a work to be machined and the works are processed in order at a plurality of processes. In terms of ensuring positioning accuracy and stable clamping performance, such a processing machine generally includes a drive source (actuator) on the pallet so that the pallet can clamp a work in a reliable manner.
On the contrary, to simplify the structure, there has been proposed a pallet jig which can clamp a work only by the action of a spring and which does not require a drive source on the pallet. For example, Japanese Laid-open Utility Model Application No. Hei-6-3541 (paragraphs [0008] to [0012] and FIG. 1) discloses such a pallet jig.
However, providing a drive source on the rotary table arises the following drawbacks that a malfunction of the operation occurs or the durability deteriorates due to cutting fluid or cleaning liquid entering into the driving cylinder during the processing, and that the size of the whole processing machine increases.
Although the pallet jig disclosed in this Japanese Laid-open Utility Model Application No. Hei-6-3541 does not require a drive source on the pallet, there is a drawback that the pallet is not applicable to works having different sizes in accordance with different kinds or types.
In view of the above, the present invention seeks to provide a clamping apparatus for works, which is suitable for use with works having a reference hole, which contributes to downsize the apparatus, which improves the durability of the drive source, and further which can be switched for different kinds or types having a different reference hole.